Diagnosis of bladder carcinoma using protoporphyrin IX fluorescence induced by 5‐aminolaevulinic acid

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Abstract
Objective: To report the results of a clinical study investigating the diagnosis of malignant and dysplastic bladder lesions by protoporphyrin IX (PPIX) fluorescence and to compare them with those from earlier studies.Patients and methods: The study included 55 patients with suspected bladder carcinoma (at initial diagnosis or at tumour follow‐up visits); 130 bladder biopsies from 49 patients were classified by pathological analysis. All patients received an intravesical instillation of 50 mL of a 3% 5‐aminolaevulinic acid (ALA) solution a mean of 135 min before cystoscopy, which was then performed under white and blue light. Malignant/dysplastic lesions showing red fluorescence under blue‐light excitation were noted and the increase in detection rate calculated.Results: There were 63 benign and 67 malignant/dysplastic areas biopsied; 10 malignant/dysplastic lesions (four transitional cell carcinoma, two carcinoma in situ, four dysplasia) were not detected during routine white‐light cystoscopy but were identified under blue light. Fluorescence cystoscopy improved the overall diagnosis of malignant/dysplastic bladder lesions by 18% over standard white‐light cystoscopy. The improvement was greater for dysplastic lesions and carcinoma in situ (50%). However, the improvement over standard cystoscopy was less than that found by other groups.Conclusion: The ALA‐based fluorescence detection system significantly enhanced the diagnosis of malignant/dysplastic bladder lesions. However, determining the optimum drug exposure time requires further investigation using well‐characterized instrumentation and study protocols, which would then allow comparison of the results from different groups.